1. Field of the Invention
The embodiment relates to an image sensor and a method for manufacturing the same.
2. Description of the Related Art
An image sensor, which is a semiconductor device converting an optical image into electrical signals, may be characterized as a charge coupled device (CCD) image sensor or a Complementary Metal Oxide Silicon (CMOS) image sensor.
The CMOS image sensor includes a photodiode and MOS transistors in a unit pixel to sequentially produce and detect electrical signals in a switching manner, implementing an image. The CMOS image sensor includes transistors and a pixel arrays in which the photodiode is electrically connected to the transistors on a semiconductor substrate. An insulating film structure including one or more wiring layers and a bond pad is formed on the pixel arrays. The pad is mainly formed by a conductive metal connected to an internal wire and is exposed from the insulating film structure in order to electrically connect the pad to an external wire.
A color filter array for detecting different colors and/or implementing a color image of the image sensor is formed on the insulating film structure. And then, a photoresist film is applied on the upper surface of the color filter array and a reflow process is performed, forming a microlens providing light condensed into the pixel array.
However, as the design rule of the image sensor gradually reduces, the size of the unit pixel reduces. Thereby, the light quantity incident on the microlens from outside the image sensor also reduces so that it becomes relatively difficult to sense light in the photodiode. In order sensitivity in the photodiode, the length that the external incident light travels from the microlens to the photodiode should be reduced. Therefore, to reduce the focal length, the height of the wiring and interlayer dielectric layer on the photodiode may be reduced.